This invention relates to a hot-melt adhesive coating machine, and more particularly, to a reactive hot-melt adhesive coating machine which applies a reactive hot-melt adhesive sprayed out of nozzles unto an applied object. The reactive hot-melt adhesive used in this machine is molten in a heated condition and curable when reacting with moisture content in ambient air.
Conventional reactive hot-melt adhesive coating machines are constructed to spray a reactive hot-melt adhesive out of a plurality of nozzles of a plurality of spray means. The reactive hot-melt adhesive is supplied from an adhesive supply means having an adhesive storage tank, which stores the reactive hot-melt adhesive in a molten condition, through an adhesive feeding passage with an appropriately pressurized air. The reactive hot-melt adhesive coating machine as constructed above has a problem that, after a coating operation with the spray means spraying out the reactive hot-melt adhesive, the reactive adhesive remaining within the nozzles is cured as a result of reacting with moisture in the ambient air, and the cured adhesive causes nozzle clogging. To avoid nozzle clogging, a known preventive measure is to saturate the heads of the nozzles in water-free oil after operation.
However, this a preventive measure for avoiding nozzle clogging requires the structure of the reactive hot-melt adhesive coating machine to have an oil tank and therefore becomes complex. Also, removing the oil from the nozzles takes substantial time. Further, the conventional apparatus still has another problem that the cured reactive hot-melt adhesive accumulated in each operation clogs the nozzles, as after each operation during the period between the end of the operation and the nozzles are saturated in the oil, a little amount of the reactive hot-melt adhesive remained at the opening of the nozzles is cured as a result of reacting with moisture in the ambient air.